A digital video recorder (DVR) is an electronic device or application software that records video or other media content in a digital format to a storage device for playback to a user in a time-shifted manner. Such digital video recorder may be embodied in a device (e.g. a set-top box, or a set-back box) connected to a television set, in circuitry built-in with a television set, or simply be a software application being executed on a computer.
At present, a conventional DVR continually records live broadcast or scheduled video programs to its internal hard disk drive (“HDD”). The programs being recorded typically correspond to the channels to which the internal tuner or tuners of the DVR are tuned. This constant recording operation to the HDD enables the user to perform time-shifted viewing and other associated time-shifting functions in connection with the recorded media content. Furthermore, the time-shifted viewing may be provided instantaneously to the user as the program is broadcasted or otherwise transmitted to the DVR. In particular, a user can perform the time-shifting functions before the entire program has been recorded. These time-shifting operations include: pause, resume, and play back of video content at various search speeds of backward play and forward play.
For a conventional DVR, the recording operation is performed regardless of whether the user is viewing any of the recorded or live-broadcast content. In fact, most DVR set-tops remain in a standby mode and continue to record content even when the user selects the power-off button. In particular, conventional DVR set-tops implement the continuous recording operations in circular recording buffers, also known as “circular buffers”, on a fixed-size portion of the HDD. When the fixed-size portion gets full, the DVR continues recording by “circling” back to an earlier recorded portion of the recording buffer and overwrites the earlier recorded content, hence the term “circular buffer.” Since the conventional DVR records over the same physical storage medium repeatedly over time, the storage medium may be subject to wear.
A conventional DVR implemented with a HDD can enjoy a relatively longer service life than a conventional DVR implemented with, for instance, a solid state drive (SSD). This is because the magnetic storage media in HDD has a relatively longer service life in terms of write cycles. For example, a typical SSD only has a service of approximately 100,000 write cycles. For recording high-definition programs on a 1-hour circular buffer, a SSD will wear out in a little over one year. Although there are SSD life-extending techniques such as “wear-leveling” (techniques to spread the write operation over all of the available SSD), the bottom line is that SSD still has a limited life-span regardless of its capacity because data is written to the entire SSD over time.
It should also be noted that if the SSD size is increased to compensate for better wear-leveling, such an increase can result in a cost increase that reduces the main benefit of using a less expensive SDD over a HDD for circular buffering.
Therefore, it is desirable to construct DVR with the less expensive SSD as long as the problem of wear is addressed.